What is the technical difference between conformal and angle-based unwrapping?
Conformal
Uses LSCM (Least Squared Conformal Mapping). This usually gives a less accurate UV mapping than Angle Based, but works better for simpler objects.
(As describled by blender user manual)

Attached is the link to the White paper on LSCM

http://www.cs.jhu.edu/~misha/Fall09/Levy02.pdf
http://alice.loria.fr/publications/papers/2002/lscm/lscm.pdf